This invention relates to an elevator including multiple elevator cages which ascend and descend in a cylindrically shaped elevator support.
Conventional elevators usually have a winding drum located in the uppermost section of a support having a rectangular cross section, the drum being connected by a cable to the cage. These elevators transport passengers or freight by winding and unwinding the cable in order to raise and lower the cage suspended from the cable.
However, recent trends show a continuing proliferation of high-rise buildings. If, for example, the number of stories in a building is tripled and the speed, passenger capacity, and number of the elevators remains unchanged, the traffic capacity is reduced to one-third the original level. The measures which have heretofore been undertaken to correct this problem have been to increase the speed of the elevators, and/or increase the size of the cages to create larger passenger capacities, and/or increase the number of the elevators.
If the elevator speed is increased to correct the problem, because the riding comfort decreases as the rate of acceleration increases, the rate of acceleration is normally limited to 0.75 m/sec.sup.2.
At a rate of acceleration of 0.75 m/sec.sup.2, the acceleration distances (in meters) required to reach the speeds of 100 m/min, 150 m/min, 300 m/min, and 600 m/min from a standstill are 1.85 m, 4.16 m, 16.65 m, and 66.65 m, respectively. If the height of one story is assumed to be 3.3 m, the acceleration distance required to reach a speed of 300 m/min from a standstill is equivalent to 5.0 stories, and the acceleration distance required to reach a speed of 600 m/min from a standstill is equivalent to a 20.2 stories.
With a high-speed elevator capable of running at a speed of 600 m/min, when traveling up to the high level of the 40th floor, half of the time is spent accelerating, and the remaining half of the time is spent decelerating. Thus, the 10 passengers are subjected to either acceleration or deceleration throughout their time on the elevator, resulting in poor riding comfort. Furthermore, the high-speed function can seldom be accomplished. The elevator's high speed of 600 m/min is effective only in the very limited case of non-stop operation to very high levels above the 40th floor, and thus there is no multipurpose usefulness.
With either the method of increasing the passenger capacity by enlarging the size of the elevator cages or the method of increasing the number of elevators, the amount of building space which must be allotted to the elevators increases, which decreases the usable business or living space of the building and reduces the efficiency of either method. Note also that the method of enlarging the size of the elevator cages does not necessarily lead to a reduction of the waiting time.
FIG. 8 of the drawings shows a comparison of the ascent-descent times with respect to the building height when the speed of the elevator cage is changed. The height of the building is shown on the horizontal axis and the round-trip ascent-descent time is shown on the vertical axis. Because the percentage of time required for acceleration increases as the speed increases, the limit for high-rise buildings of 30 stories or less is a speed of approximately 150 m/min, due to the inability to make sufficient use of a high-speed function.
In consideration of the problem described above, the objective of this invention is to propose an efficient elevator system for which the waiting time is substantially reduced without increasing the number of elevators.